space-travel

What would actually happen as you approached the speed of light? The energy bill diverges, your clock slows, the sky bunches up ahead of you, and the empty space between stars turns into a particle beam. The reason the limit exists is more interesting than the scenario.

The nearest star is 4.24 light-years away — roughly 40 trillion kilometres. Reaching it with current technology would take 80,000 years. What would it actually take to become a civilisation that spans multiple star systems?

Astronauts return from space slightly younger than they would have been on Earth. The explanation is real physics — Einstein's theory of relativity — and it has measurable consequences for everything from GPS to interstellar travel.